On the water surface, the submarine is powered by two sets of MTU engines. While submerged, the Kockums-built Stirling engine AIP system is used to drive a 75-kilowatt (101 shp) generator for either propulsion or charging the batteries. A Stirling engine is particularly well suited for a submarine because the engine is near silent and can use the surrounding sea water as a heat sink to increase efficiency. Submerged endurance is dependent on the amount of liquid oxygen stored on-board and is described as "weeks". The class is characterized by its low acoustic signatures, extreme shock resistance, and a competent combat system.[2]

Kockums touts extreme maneuverability for this class due to the hull design and a well-placed X rudder. The X rudder provides four control surfaces, along with two mounted on the sail, which enables sharp turns and the ability to operate very close to the seabed. Ship automation and computerized steering allow a single operator to steer the submarine in depth and course, which also results in a smaller crew complement, leading to good accommodation standards and low operating costs.[3]

The class has many features that enhance stealth, helping it to remain undetected. All shipboard machinery is isolated and mounted on rubber dampeners to reduce vibrations and noises; a hydrodynamic hull design reduces noise, infrared signature, and active sonar response, counteracting its magnetic signature with 27 independent electromagnets, and short circuiting extremely low frequency (ELF) electrical fields; various hull coatings reduce active sonar response, and coating the mast with radar-absorbent material. Combined with the near-silent operation of the Stirling generator and slow-turning propeller to prevent cavitation, the boats are very difficult to detect under water, especially in their normal area of operations, the Baltic Sea.[3]

After being refit and upgraded to sustain the higher temperatures of tropical water,[4] HMS Halland took part in a multi-national exercise in the Mediterranean from September 16, 2000. Allegedly, there she remained undetected while still recording many of her friendly adversaries, attracting interest from the participating countries. In early November the same year, she participated in a NATO "blue-water" exercise in the Atlantic. There, she reportedly won a victory in a mock "duel" with Spanish naval units, and then the same in similar duel against a French SSN, a nuclear-powered attack submarine. She also "defeated" an American SSN, the USS Houston.[4]

In March 2013, Kockums received an order for an overhaul for two of the Gotland-class submarines. The overhaul is expected to be completed by 2017. With these upgrades, the submarines will be able to remain in active duty until after 2025.[14] On 2 April 2014, the Swedish defence minister announced that all three submarines are to be overhauled.[15]